Commit 89497968 authored by Heiko Carstens's avatar Heiko Carstens Committed by Vasily Gorbik
Browse files

s390/ftrace: provide separate ftrace_caller/ftrace_regs_caller implementations 



ftrace_regs_caller is an alias to ftrace_caller - making ftrace_caller
quite heavyweight. Split the function and provide an ftrace_caller
implementation which comes with fewer instructions. Especially getting
rid of 'stosm' on each function entry should help here, e.g. to
have less performance impact on live patched functions.

Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 176510eb

arch/s390/include/asm/ftrace.h

+0 −1
Original line number Diff line number Diff line
@@ -17,7 +17,6 @@ 


void ftrace_caller(void);



extern char ftrace_graph_caller_end;

extern void *ftrace_func;



struct dyn_arch_ftrace { };

arch/s390/kernel/mcount.S

+29 −12
Original line number Diff line number Diff line
@@ -33,13 +33,15 @@ ENDPROC(ftrace_stub) 
#define TRACED_FUNC_FRAME_SIZE	STACK_FRAME_OVERHEAD

#endif



ENTRY(ftrace_caller)

	.globl	ftrace_regs_caller

	.set	ftrace_regs_caller,ftrace_caller

	.macro	ftrace_regs_entry, allregs=0

	stg	%r14,(__SF_GPRS+8*8)(%r15)	# save traced function caller



	.if \allregs == 1

	lghi	%r14,0				# save condition code

	ipm	%r14				# don't put any instructions

	sllg	%r14,%r14,16			# clobbering CC before this point

	.endif



	lgr	%r1,%r15

	# allocate stack frame for ftrace_caller to contain traced function

	aghi	%r15,-TRACED_FUNC_FRAME_SIZE
@@ -49,13 +51,30 @@ ENTRY(ftrace_caller) 
	# allocate pt_regs and stack frame for ftrace_trace_function

	aghi	%r15,-STACK_FRAME_SIZE

	stg	%r1,(STACK_PTREGS_GPRS+15*8)(%r15)



	.if \allregs == 1

	stg	%r14,(STACK_PTREGS_PSW)(%r15)

	lg	%r14,(__SF_GPRS+8*8)(%r1)	# restore original return address

	stosm	(STACK_PTREGS_PSW)(%r15),0

	.endif



	lg	%r14,(__SF_GPRS+8*8)(%r1)	# restore original return address

	aghi	%r1,-TRACED_FUNC_FRAME_SIZE

	stg	%r1,__SF_BACKCHAIN(%r15)

	stg	%r0,(STACK_PTREGS_PSW+8)(%r15)

	stmg	%r2,%r14,(STACK_PTREGS_GPRS+2*8)(%r15)

	.endm



SYM_CODE_START(ftrace_regs_caller)

	ftrace_regs_entry	1

	j	ftrace_common

SYM_CODE_END(ftrace_regs_caller)



SYM_CODE_START(ftrace_caller)

	ftrace_regs_entry	0

	j	ftrace_common

SYM_CODE_END(ftrace_caller)



SYM_CODE_START(ftrace_common)

#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES

	aghik	%r2,%r0,-MCOUNT_INSN_SIZE

	lgrl	%r4,function_trace_op
@@ -74,24 +93,22 @@ ENTRY(ftrace_caller) 
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

# The j instruction gets runtime patched to a nop instruction.

# See ftrace_enable_ftrace_graph_caller.

	.globl ftrace_graph_caller

ftrace_graph_caller:

	j	ftrace_graph_caller_end

SYM_INNER_LABEL(ftrace_graph_caller, SYM_L_GLOBAL)

	j	.Lftrace_graph_caller_end

	lmg	%r2,%r3,(STACK_PTREGS_GPRS+14*8)(%r15)

	lg	%r4,(STACK_PTREGS_PSW+8)(%r15)

	brasl	%r14,prepare_ftrace_return

	stg	%r2,(STACK_PTREGS_GPRS+14*8)(%r15)

ftrace_graph_caller_end:

	.globl	ftrace_graph_caller_end

.Lftrace_graph_caller_end:

#endif

	lg	%r1,(STACK_PTREGS_PSW+8)(%r15)

	lmg	%r2,%r15,(STACK_PTREGS_GPRS+2*8)(%r15)

	BR_EX	%r1

ENDPROC(ftrace_caller)

SYM_CODE_END(ftrace_common)



#ifdef CONFIG_FUNCTION_GRAPH_TRACER



ENTRY(return_to_handler)

SYM_FUNC_START(return_to_handler)

	stmg	%r2,%r5,32(%r15)

	lgr	%r1,%r15

	aghi	%r15,-STACK_FRAME_OVERHEAD
@@ -101,6 +118,6 @@ ENTRY(return_to_handler) 
	lgr	%r14,%r2

	lmg	%r2,%r5,32(%r15)

	BR_EX	%r14

ENDPROC(return_to_handler)

SYM_FUNC_END(return_to_handler)



#endif